Study On Therapeutic Effect Of Nudemice Model With Human Nasopharyngeal Carcinoma Induced By Photocatalytic Nano-TiO₂

Objective： To study the therapeutic effect of nudemice model with humannasopharyngeal carcinoma induced by photocatalytic nano-TiO₂, and explore itspossible mechanism of tumor inhibition, assess its impact on the body, expecting tooffer some theoretical and experimental evidences for researching and applyingnano-TiO₂photodynamic therapy to clinical treatment nasopharyngeal carcinoma.Method： To establish the experimental model of nudemice bearing humannasopharyngeal carcinoma xenograft, and randomly divide them into six groups,including the experimental group: the concentration gradient of nano-TiO₂+UVirradiation. Negative control group: a simple set of nano-TiO₂alone group and UVirradiation alone group and blank control group. The nano-TiO₂suspension wasinjected into xenograft tumor, and24h after UV light which wavelength ranged330-400nm treatment, all tumor tissues were acquired and sectioned, stained HE forpathological analysis. Tumor cells ultrastructural changes and apoptosis was observedby transmission electron microscope（TEM）. The expression of caspase-3wasexamined with technique of immunohistochemical staining and the apoptotic cellswere detected with method of TUNEL, and correlation between them was analyzed inorder to preliminarily explore the mechanism of tumor cells apoptosis.Results：1, By pathological analysis, the local inflammatory response of tumor tissuesafter nano-TiO₂photodynamic therapy was significant（grade Ⅱ, Ⅲ）, with theinflammatory response was the formation of local necrosis, but not evidentinflammatory response in the negative and blank control group（gradeⅠ）. Under highmagnification, no acute inflammation or tissue injury was detected in livers andkidneys of all groups.2, Under TEM, we observed that the nano-TiO₂particles enter into the cytoplasm and the nucleus in the experimental groups, besides, many tumor cells hadmorphological changes of apoptosis.3, The positive expression of caspase-3and positive cells marked by TUNEL inthe experimental groups were significantly more than the control groups （P <0.01）,and the effect enhanced with nano-TiO₂concentration increasing （P <0.01）.Conclusion：1, The expression activity of tumor tissue caspase-3could beenhanced under nano-TiO₂photodynamic therapy so as to induce apoptosis and inhibittumor growth, and the effect was nano-TiO₂concentration-dependent within a certainrange.2, By inducing tumor cells apoptosis and mediated inflammation response toplay the role of tumor suppressor maybe was its possible mechanism.3, No significant side effects were found on the body, which will provide reliableexperimental protection for applying the technology of photocatalytic nano-TiO₂toclinical treatment of nasopharyngeal carcinoma.